1. Field of the Invention
The present invention relates to a solid-state dye laser in which a solid-state dye is used.
2. Description of the Related Art
A liquid dye laser, a solid-state dye laser, and the like are known as a tunable organic laser in which the wavelength can be tuned in a visible range.
In a liquid dye laser, a laser dye solution is circulated; therefore, there are advantages in that degradation of the laser dye is unlikely to affect the laser and replacement of the solution is possible. However, in order to use a solution, a solution tank, a circulator for circulating a solution, and the like are needed, which causes a problem of the apparatus being large.
On the other hand, a solid-state dye laser can be compact since a thin film of laser dye is used; however, a thin film of laser dye that is once formed cannot be replaced and thus, it is crucial to suppress degradation of the laser dye thin film.
A coherent light source (various lasers: for example, a gas laser such as an excimer laser and a solid-state laser such as a NdYAG laser) is normally used as an excitation light source (also referred to as a light source in this specification) for operation of a dye laser. In the case of using an incoherent light source such as a xenon lamp, a halogen lamp, a light-emitting diode, or the like as an excitation light source, it is not easy to obtain light by laser emission from a solid-state dye. To obtain light by laser emission, it is necessary to reduce the laser threshold (light density of the excitation light source per unit of time), and for example, it is reported that the laser threshold is reduced by provision of a resonator structure which does not leak light by stimulated emission and by irradiation of dye molecules with excited light with high density; accordingly, laser emission is easily caused (e.g., see Patent Document 1).
For emission of a laser beam from a solid-state dye laser, it is necessary that a solid-state dye is irradiated using an excitation light source having a high light intensity per unit area (light density) and absorption of light with high density is induced in the solid-state dye. For this purpose, a coherent light source with high light density is usually used as the excitation light source. In the case of not using a laser light source, irradiation needs to be performed in such a manner that light from an incoherent light source such as various lamps is gathered with a lens or the like to increase light density. In the case of irradiating a solid-state dye with light having high density using either laser light or incoherent light, it is difficult to use a plane light source which is in contact with a solid-state dye film. Even using a thin the solid-state dye film, there is a limit in miniaturization of the entire dye laser system including an excitation light source. Therefore, it has been considered that thinning the entire system would be impossible.
[Reference]
    [Patent Document 1] Japanese Published Patent Application No. 2004-282012